[AVRO-1568] Allow Java polymorphism in Avro for third-party code

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.7.6
• Component/s: java
• Assignee: Unassigned
• Reporter: Sachin Goyal
• Created: 22/Aug/14 02:01
• Updated: 16/Apr/20 10:46

Description

A large number of Java designs interacting with databases with Hibernate/Couchbase (perhaps, even otherwise) have Java polymorphism of the form:

class Base 
{
   Integer a = 5;
}

class Derived extends Base
{
    String b = "Foo";
}

class PolymorphicDO
{
   Base b = new Derived();
}

Jackson handles this kind of field by using annotations such as:

@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class”)

If such a thing can be added to Avro, all those Java designs could become immediately usable with Avro. They would also become Hadoop compatible due to AvroSerde.

Issue Links

• is related to: AVRO-1569 ReflectData.AllowNull fails with polymorphism
• is related to: AVRO-1570 ReflectData.AllowNull fails with polymorphism and @Union annotation